Attachment plug cap



Jan. 9, 1940. .l N. cHlRELsTElN 2,186,751

ATTACHMENT PLUG CAP Filed March 1, 1938 INVENTOR versmaden.. 9', "1940 UNITED STATES PATENT OFFICE claims. 'milles-ssn The invention herein disclosed relates to' sepl arable electrical connectors vin the nature of attachment plug caps. Y Y Special objects of the invention are to provide 5 a. cord clamp for devices of this nature, which can be readily fully opened to receive the cord and which will automaticallyjcenter/ itselfin.'

gripping engagement with the cord.

Other objects are to simplify and improve'the 1 .each having an angled base- I9, at one end. piv- 10 structure generally of attachment plug capsu-.z

Further objects and novel features of constru l tion, combinations and relations ol'- parts'` by] which the objects of the invention are attained are set forth hereinafter and will be apparent from the following specication in conjunction with the accompanying illustration.'

The drawing which may be consideredas forming part of the followingspeciiication illustrates practical and at present preferred embodiments of the invention. The structure however may be modified and changed within thesc'ope of the invention as will be apparent from the follow: ing description and the broadscope of the claims defining the invention.`

Fig. 1 is a broken top plan-view of an attachment plug cap embodying the invention and shown with the cord clamp in opened relation to receive the cord.

Fig, 2 is a generally similar view showing the clamp closed on the cord and the latter appearing in section.

Fig. 3 is a side view of the cap. f Fig. 4 is a bottom plan view showing the open unobstructed character of the cord passage when the clamp is fully opened.

Fig. 5 is a side elevation with parts 'broken and in section as on line 5-5 of Fig. 2. i

Fig. 6 is a broken detail illustrating'y the piv- Otal mounting for onevof the clamp members. Figs. '7, 8 and 9 are broken sectional details of modifications. y* y In the several views, the body of the plug cap is designated lll, and is shown as'car'rying attachment plug prongs il, projecting from one face of the same. These prongs are shown as secured simply by yordinary elongated tubular eyelets or hollow rivets I2, engaged over the bases I3, of the contact blades at one end and headed over at the opposite end into an annular groove I4, at the opposite side of the plug body.

To avoid any possibility of the short circuiting of these blade securing eyelets, an annular disc I5, of insulating material is shown seated in groove i4, over the upper ends of the eyelets.

The body l0 which may be oi resilient live rubber is-reinforced'in the present disclosure by 'a plate I8, shown'as secured over the upper end or topV of the cap byelongated tubular rivets or eyelets I'l,` extending-entirely throughA the body.

, Inl addition to serving as a` reinforcement for B the bodyithis plate serves as a. mounting and support forv the lcord clamp. f

The cord clamp comprises two duplicate clampingv members l8,in ythe nature of levers,

`otalh(secured on'the plate I5, as by a shouldered alongitudinal'slot 2l, receiving the shank of a headed screwf22,'threaded into the other companion clamp vleverat 23, at a point inside or 15 toward thecenter fromzthe pivot stud of that Vexpose the cord passage 24.'v through the center .20

plug, enabling easy threadingfofgzthe' cord 25, into the plug.- The.- tightening-I. of leither screw will have a closing and at thesarne time a centering 'effect' en the vtwo .clamp .-levers,' so thatv either screw may be startedy :iirst' and the. final 25 tightening accomplished byv turning both screws Vto substantially equal tension. .Inthe nrst portion of the tightening movement, the screwbeing turned will have thefeifectof iirstdrawing in the free endof' the lever which it engagea Then` as. that lever begins tn take'hold` of the. cord, the pull 'of the screw will have the effect of swinging inwardv the other lever which carries the screw seat for that screw. "As the levers approach a more nearly closed relation, thepull 35 .comes more nearly over the center of the leverA pivots 20, as in Fig. 2, so that then the vscrews act almost as pulling directly against; said pivot mounts. .Under all these conditions of adjustment, the two levers will continue their sub- 40A stantially parallel relationship, substantially equally centered with respect to the cord passage and gripping the cord substantially equally at Opposite sides. In the final relationship, the

cord is held properly centered -at theend of the is plug cap, substantially as indicated in Fig. 5.

'I'he clamp mounting plate IS.- may have thev edge of the same flanged inwardly as indicated at 26, Fig. '7, or 21, Fig, 8, to stiften it and to provide a rounded outer shoulder 28. This edge 50 reinforcement enables a relatively light gage plate to be usedy for supporting thev cord clamp and which does not add robjectlonably to the weight of the cap. If desired, the end of the body may be formed with a narrow annular 55 groove 29, to receive the edge ange of the clamp plate or the edge flange may be left somewhat sharpened as in Fig. 8, so that it will bite somewhat into the end surface when the body is formed of resilient material.

When the body is made of resilient material, the annular insulating washer I5, overlying the ends of the blade fastening eyelets serves the further purpose of insuring against short circuiting in the event that excess pressureA is applied to the plug, such as might deform the body sumciently to force the ends of the prong rivets into engagement with the clamp mounting plate. This mounting plat'e actually is simply a washer, having at the center an opening 30, somewhat larger than the cord passage in the body. The reinforcement gained by anging the end of this washer as in Figs. 7 and 8, permits the washer to be made of light thin stock. 'I'he groove |4 into which the fastening eyelets extend may be quite narrow, that is, simply the width of the eyelet heads and quite shallow as the anging of these eyelets takes up but small space. 'I'he insulating washer I5, while probably not essential, is considered desirable as providing a definite layer of insulation between the ends of the contact fastenings and the supporting plate.. By locating the clamp pivots 20, for the two levers diametrically opposite and at opposite sides of the cord passage, the levers will be maintained in parallelism in the various positions of adjii'stment. This also enables the pivotally mounted end portion 3| of one lever to act as a positive stop for the slotted free end portion 32 of the other lever, thus to prevent the levers from. ever moving closed past the center of the cord passage. By providing the seats 23 for the screws 22, in the pivoted end portions 3|, of the levers and the slots 2|, in the free ends of the levers, the screws maintain their approximate parallelism as they are tightened as will be apparent from Figs. l and 2.

As shown in Fig. 9, the end plate I8 may be increased to substantially the full diameter of the plug body and have an edge flange 33, seating over a shouldered portion 34, at the very edge of the plug. The coaction of the flange with this shouldered portion automatically centers the plate over the end of the plug and to an extent contines the plug so'that it can not be distorted under unusual pressure. This provides a desirable plug construction, which in some instances, may be used without the clamp structure.

What is claimed is:

1. In an attachment plug cap, a plug body having a cord passage therethrough, a supporting plate at one end of said body. clamp levers having angled bases, means pivotally mounting the angled bases of said levers on the outer face of said supporting plate at opposite sides of said cord passage and in position with the free end of one lever oppositel the pivoted angled base portion of the other lever and screws connecting said opposed free and Asaid pivotally mounted end portions of the clamp levers, said screws being set inwardly toward the cord passage from the pivotal mounts of said levers.

2. An attachment plug cap having a central on said plate at opposite sides of the cord passage with the free end of one lever adjacent the pivotally mounted end of the other lever and screws connecting the free ends of the levers with said pivotally mounted ends of the levers, said screws being disposed inward of the pivotal mountings toward the cord passage.

3. An attachment plug cap, comprising a resilient plug body havinga narrow annular groove in one end, an end plate engaged over said end of the plug body and having an inwardly angled edge ange entered in said narrow annular groove, means securing said plate in flat abutting engagement over the end oi said resilient plug body, said plate and plug body having passages Ior a cord, opposed cord clamping levers having angled ends engaged with said end plate at opposite sides of the cord passage therethrough, means pivotally securing said angled ends of said levers on said end plate and screws adjustably securing opposite end portions of said levers together.

4. An attachment plug cap comprising a resilient plug body having a cord passage therethrough and provided with a narrow annular groove in one end of the same adjacent the rim portion of the plug body, an annular end plate engaged over said end of the plug body, having a central cord passage and having a perlpheral angularly projecting flange entered in said annular groove in the end of the plug body. opposed substantially parallel cord clamp levers, means pivotally mounting one end of each of said clamp levers over the outer face of said annular end plate at opposite sides of the cord passage and with the pivoted end of one lever opposite the free end of the other lever and screws adjustably securing the opposed end portions of said levers together.

5. An attachment plug cap, comprising a resilient plug body having a cord passage therethrough, a thin flat annular end plate secured over one end of said plug body and having a central cord passage in line with the cord passage in the plug body, opposed substantially parallel cord clamp levers, means pivotally mounting one end of each of said clamp levers over the outer i'ace of said annular end plate at opposite sides of the cord passage and with the pivoted end of one lever opposite the free end of the other lever, one end of each lever having a screw seat .and the opposing end of the other lever having a slot in line with the screw seat in the rst mentioned lever and screws extending through said slots into engagement with said screw seats for drawing the free ends of the levers toward the pivoted ends of the levers in substantially parallel cord clamping relationship.

NATHAN CHIRELSTEIN. 

